Electron paramagnetic resonance of stressed fibre nylon 6: annealing effects

The temperature dependence of the electron paramagnetic resonance (EPR) spectra of 'high tension' (HT) and 'low tension' (LT) nylon 6 fibres has been measured in the X-band. The spectra show a characteristic hyperfine structure owing to coupling to the nitrogen nucleus and occur due to nitroxide additives. The linewidth transitions signalling the onset of self-diffusion occur at much higher temperatures than in the proton NMR spectra. The higher resolution of the EPR data allows for discrimination between HT and LT fibres and the observation of the effects of the super-structure induced by different thermo-mechanical treatments on the molecular self-diffusion.